February 15, 1873.] THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
G51 
at pleasure. [The lecturer here placed some glass ves¬ 
sels—bottles, flasks, and closed tubes—over a small jet 
of burning hydrogen, when the musical tones were im¬ 
mediately produced.] 
About 1800, two Italian philosophers, Messrs. Brug- 
natelli and Pictet, published some experiments upon this 
subject, and showed that closed vessels were not by any 
means essential, open tubes with a little care in the ma¬ 
nipulation being as successful; to ensure this success, 
however, they believed that the surrounding vessel or 
tube must be made of a sonorous or elastic substance, 
such as glass, earthenware, metal, or dry polished wood; 
they also further observed the effect of lengthening or 
shortening the tube, upon the tone produced. [Open 
tubes of glass, metal, etc., were here placed over the pre¬ 
viously used hydrogen flame, when shrill musical notes 
were emitted ; a tube, capable of being lengthened and 
shortened at pleasure, was also placed over the same flame, 
when the falling and rising of the note was very evident.] 
In 1802, De la Rive published in the Journal de Physic 
some researches upon “ The Sounds Produced by Hy¬ 
drogen Gras in Tubes.” This was by far the most elabo¬ 
rate and exhaustive essay upon the subject up to this 
time, and it contains many new facts, setting forth at 
•the same time a theory which endeavoured to account 
for the production of these sounds, no explanation having 
been attempted by either of the previous experimenters. 
The principal statem ents in De la Rive’s paper were, 1st, 
it was essential that the tube, or vessel, should be elastic 
—“suitable for an echo”—capable, that is to say, of 
reverberation; 2nd, the flame to be obtained from hy¬ 
drogen gas, all other inflammable bodies being found un¬ 
successful ; 3rd, his conception that the condensation 
and reformation of aqueous vapour was the origin of the 
sound vibrations. 
All sound of whatever nature is produced by vibra¬ 
tion, the body sounding being in a state of rapid motion. 
In the case of sound that appeals to our sense of hearing 
as noise, the motion is irregular, and not very rapid. 
In the case of a musical note, the motion is perfectly 
regular, periodic, and is also sufficiently rapid. A noise 
repeated after regular intervals more rapidly than thirty- 
two times in a second becomes lost or merged in a musical 
note, the pitch of this note depending upon the rapidity of 
such vibrations, up to about 40,000 vibrations per second, 
when most ears lose their power of distinguishing sounds. 
[These points were well illustrated by the rattling of 
nail3 upon a tin tray, and the musical note produced by 
a vibrating tuning-fork, also by the musical note ob¬ 
tained by the oscillation of a grooved block of hot copper 
upon the edge of a cold block of lead.] 
By De la Rive’s supposition these periodic and suffi¬ 
ciently rapid vibrations were set up and maintained by 
the condensation and rarefaction of aqueous vapour, pro¬ 
duced by the combustion of the hydrogen in the air. 
This theory might possibly have been rejected at once 
had it not been supported by a most ingenious and 
favourable experiment. De la Rive was able to succeed 
in producing a musical note by aqueous vapour alone. 
Placing a small quantity of water in the bulb of a 
thermometer tube, and rapidly boiling the water, the 
steam which was thus formed was unable to issue entirely 
from the tube, but was to a great extent condensed into 
drops of water in the stem, whence falling back into 
the bulb, it became immediately reconverted into steam, 
this alternation being sufficiently rapid to give rise to a 
distinct musical note. It was supposed by the author 
that these primary vibrations were taken up, exalted, and 
reverberated by the walls of the tube, the final result 
being quite perceptible to the ear. 
The German philosopher Chladni observed in 1802 
that the sounds emitted by these “ musical flames” were 
identical with the notes given out by the tubes surround¬ 
ing the flames when sounded by themselves. He also 
obtained in one experiment a note and its octave from 
the same tube. 
[A tube being placed in front of the lips, and blown 
across gave out a certain note which was heard to be 
identical with the note produced when the same tube 
was inverted over the burning hydrogen flame.] 
Up to this period very little systematic attention had 
been bestowed upon this subject, but in 1818 Mr. Fara¬ 
day was requested by some of the members of the Royal 
Institution to investigate it, and with his invariable care 
and completeness in work, was speedily able to explain 
most of the facts hitherto observed in the most satisfac¬ 
tory manner. 
De la Rive’s theory of aqueous vapour was criticized, 
and found wanting. Faraday, proving that the tones 
might be produced as easily, at a temperature far too 
high to allow aqueous vapour to condense, as at a lower 
one. Further, he succeeded in obtaining the same sounds- 
from a burning jet of carbonic-oxide, which as. it con¬ 
tained no hydrogen was incapable of producing any 
aqueous vapour whatever. Other inflammable gases- 
and substances were found to yield musical notes, with 
some little difference of arrangement and care in manipu¬ 
lation ; all the inflammable gases—ether, alcohol, and 
even wax and tallow—being found effective. 
The belief held by all previous experimenters that the- 
tube must necessarily be formed of an elastic or sonorous 
substance was found to be erroneous; tubes of papery 
cardboard, and soft wood, answering as perfectly as those- 
of glass or metal. 
[A coal gas flame produced these notes as easily as the- 
previously used hydrogen flame, and a sheet of foolscap 
paper rolled up to form a tube was shown to be effec- 
tive.] 
These experiments enabled Faraday to indicate the* 
true nature of these sounds, which he did by showing that 
the flame itself was the true origin of . the vibrations. 
When a flame is introduced into a suitable tube, the- 
current of air passing over its surface is sufficiently 
strong to draw it upwards to such an extent as to sever 
its connection with the jet; an explosive mixture.is at 
once formed of the air and the issuing gas ; this mixture 
is inflamed, and for a moment the flame and jet become 
once more united ; this action is repeated with sufficient 
rapidity as eventually to produce a musical note. These 
vibrations are taken up and exalted to this note, not by 
the tube, but by the column of air enclosed within it. 
Faraday called attention to the fact that a similar result 
to a less extent might be observed in ordinary lamps 
with chimneys, and in furnaces and fires, burning under 
tall shafts,—the roar of which was an approach to a 
musical noise. 
[Most of the above points were successfully illustrated 
as they were mentioned. The vibration of a flame, or 
its intermittent partial extinction during its song, being 
strikingly shown by means of its reflection from a rotat¬ 
ing mirror on to a white screen, when the flame was 
quiescent a straight uninterrupted band of light was 
apparent, but on sounding, this band was broken up 
into a series of distinct images of the flame, separated 
from each other by periods of darkness. 
Dr. Tyndall commenced his experiments in 1856, and 
they were published in 1857, but he has frequently re¬ 
turned to the subject since, and by a series of interesting 
and careful experiments has much elaborated it. Atten¬ 
tion was immediately directed by him to the analogy 
existing between the “ Musical Flames’ ’ and organ, pipes, 
the two being strictly comparable. In an organ pipe the 
impinging of a strong current of |air issuing from a slit, 
against a sharp piece of an elastic body called the lip,, 
is the primary cause of vibration ; the vibrations thus, 
produced vary in rapidity and in amplitude, but the 
column of air enclosed by the pipe picks out only those 
which coincide with its own length, and. compels them 
to vibrate more and more in unison with itself. By 
this means the result is to strengthen and exalt them 
to a musical tone. If we now substitute a flame for 
the first rush of air against the lip of such a pipe, the 
